[SystemInfo API] Rewrite DisplayInfoProvider without SystemInfoProvider.

chrome/browser/extensions/api/system_display/display_info_provider.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_SYSTEM_DISPLAY_DISPLAY_INFO_PROVIDER_H_
 #define CHROME_BROWSER_EXTENSIONS_API_SYSTEM_DISPLAY_DISPLAY_INFO_PROVIDER_H_
 
 #include <string>
+#include <vector>
 
-#include "base/lazy_instance.h"
-#include "chrome/browser/extensions/api/system_info/system_info_provider.h"
 #include "chrome/common/extensions/api/system_display.h"
 
 namespace gfx {
 class Display;
 }
 
 namespace extensions {
 
 typedef std::vector<linked_ptr<
     api::system_display::DisplayUnitInfo> > DisplayInfo;
 
-class DisplayInfoProvider : public SystemInfoProvider {
- public:
-  typedef base::Callback<void(bool success)>
-      RequestInfoCallback;
-  typedef base::Callback<void(bool success, const std::string& error)>
-      SetInfoCallback;
-
-  // Gets a DisplayInfoProvider instance.
+class DisplayInfoProvider {
+ public :
   static DisplayInfoProvider* Get();
 
-  // Starts request for the display info, redirecting the request to a worker
-  // thread if needed (using SystemInfoProvider<DisplayInfo>::StartQuery()).
-  // The callback will be called asynchronously.
-  // The implementation is platform specific.
-  void RequestInfo(const RequestInfoCallback& callback);
-
-  // Updates the display parameters for a display with the provided id.
-  // The parameters are updated according to content of |info|. After the
-  // display is updated, callback is called with the success status, and error
-  // message. If the method succeeds, the error message is empty.
-  // The callback will be called asynchronously.
-  // This functionality is exposed only on ChromeOS.
-  virtual void SetInfo(
-      const std::string& display_id,
-      const api::system_display::DisplayProperties& info,
-      const SetInfoCallback& callback);
-
-  const DisplayInfo& display_info() const;
-
-  static void InitializeForTesting(scoped_refptr<DisplayInfoProvider> provider);
-
- protected:
   DisplayInfoProvider();
   virtual ~DisplayInfoProvider();
 
-  // The last information filled up by QueryInfo and is accessed on multiple
-  // threads, but the whole class is being guarded by SystemInfoProvider base
-  // class.
-  //
-  // |info_| is accessed on the UI thread while |is_waiting_for_completion_| is
-  // false and on the sequenced worker pool while |is_waiting_for_completion_|
-  // is true.
-  DisplayInfo info_;
+  // Works for browser tests, which runs its own process, this doesn't work for

[oshima, 2013/09/11 02:55:40]

This is for tests that run in its own process (e.g. browser_tests).  Using this
in other tests (e.g. unit_tests) will result in DCHECK failure.

[Haojian Wu, 2013/09/11 03:09:16]

Done. Updated.

+  // unit tests where multiple tests are run within one process.
+  static void InitializeForTesting(DisplayInfoProvider* display_info_helper);
+
+  DisplayInfo GetAllDisplaysInfo();
+
+  virtual bool SetInfo(const std::string& display_id,
+                       const api::system_display::DisplayProperties& info,
+                       std::string* error);
 
  private:
-  // Overriden from SystemInfoProvider.
-  // The implementation is platform specific.
-  virtual bool QueryInfo() OVERRIDE;
-
   // Update the content of the |unit| obtained for |display| using
   // platform specific method.
-  void UpdateDisplayUnitInfoForPlatform(
+  virtual void UpdateDisplayUnitInfoForPlatform(
       const gfx::Display& display,
       extensions::api::system_display::DisplayUnitInfo* unit);
 
-  static base::LazyInstance<scoped_refptr<DisplayInfoProvider> > provider_;
-
   DISALLOW_COPY_AND_ASSIGN(DisplayInfoProvider);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_SYSTEM_DISPLAY_DISPLAY_INFO_PROVIDER_H_